1. Field of the Invention
The current invention relates to a system control unit and a method for controlling a charging system that is provided for charging an electrical energy storage device. The charging system includes an electric generator and an internal combustion engine that is mechanically connected to the generator. The current invention moreover relates to a charging system for charging an electrical energy storage device.
2. Description of the Related Art
A vehicle, in particular a watercraft, for example a submarine is generally known that includes an electrical energy storage device, for example a battery. Energy stored in the electrical energy storage device serves to supply various electricity consuming components of the vehicle with electricity. Among other things the energy storage device is used to supply an electric motor with electric current in order to drive the vehicle by way of the electric motor. Since the electrical energy storage device during its use continuously delivers energy and is thus being depleted, a charging system for charging of said electrical energy storage device is required. Electric energy is being generated by this charging system and is then stored in the energy storage device. The energy storage device is then charged.
A known charging system includes an internal combustion engine in which fossil fuel, for example diesel, is burned in order to produce a torque on an output shaft of the internal combustion engine. An electric generator is mechanically connected with the output shaft of the internal combustion engine. The generator serves to convert the mechanical energy that is generated by the internal combustion engine and that is transferred to the generator, into electrical energy. The electrical energy that is produced by the generator is then fed for storage into the electrical energy storage device.
A rated output for the internal combustion engine is normally defined such that the internal combustion engine is in a position to continuously deliver the rated output as the highest performance and to thereby guarantee a long service life for the internal combustion engine. The rated output is determined once for certain worst-case conditions that may exist in the worst case during operation of the internal combustion engine. Thus—under all circumstances that may be anticipated—a reliable operation of the charging system can be achieved for a specific application in which the internal combustion engine is used. Such a worst-case condition is, for example, the least favorable temperature of a coolant that is used for cooling of the internal combustion engine. A generator controller that serves to control the generator receives charging default setting information from a charge control unit of the energy storage device, with a charging default for an output value that is to be delivered by the generator. Such an output value is in particular an output voltage, an output current or an output of the generator. The generator controller requires such output from the internal combustion engine that the generator can meet the charging default demanded by the charge controller. However, the internal combustion engine is adjusted such that it does not provide higher performance than the rated output, even if a higher performance is demanded by the generator controller. In such a case, the generator does not receive the required output of the internal combustion engine and cannot meet the charging default required by the charge controller. In regards to its efficiency the charging system is thus not very flexible.
What is needed in the art is a flexible operation of a charging system that is provided for charging an electrical energy storage device and which includes an electric generator and an internal combustion engine.